The use of recombinant human thyrotropin and low-dose (1.1 GBq) postoperative radioiodine ablation may be sufficient for the management of low-risk thyroid cancer. (Funded by the French National Cancer Institute [INCa] and the French Ministry of Health; ClinicalTrials.gov number, NCT00435851; INCa number, RECF0447.).

This large prospective cohort of patients presented a low rate of recurrence. Initial Tg measurements allow to predict long-term recurrence with an excellent specificity. Stimulated Tg determination presented a slightly higher sensitivity than Tg determination on LT4. TSH stimulation may be avoided when Tg measured 3 months after ablation is less than 0.27 ng/ml during LT4 treatment.

Using an assay with a lower functional sensitivity may give an earlier indication of the presence of Tg in the serum on L-T4 treatment and may be used to study the trend in serum Tg without performing any TSH stimulation. Serum Tg determination obtained after TSH stimulation still permits a more reliable assessment of cure and patient's reassurance.

We have examined insulin action on glucose metabolism in six hypothyroid patients before and after regular thyroid hormone treatment, and in six healthy volunteers before and after transient induction of moderate hyperthyroidism. Insulin was infused under euglycaemic and eukalaemic clamps. An appropriate amino acid infusion was used to blunt insulin-induced decreases in amino acid levels. Glucose kinetics were assessed using a primed continuous infusion of [6,6-(2)H(2)]glucose. The results showed that basal plasma insulin and glucose levels (i.e. before infusion) were similar in each case. Despite similar insulin infusion rates, the plateau value of insulin was lower after thyroid treatment in both hypothyroid patients and healthy volunteers. The rate of exogenous glucose needed to maintain plasma glucose at a steady-state level was increased by thyroid hormone in hypothyroid patients (P <0.05), but not in healthy volunteers. Thyroid treatment resulted in a significant increase in basal glucose disposal in both groups (P <0.05). Insulin, in conjunction with glucose and amino acids, significantly stimulated glucose disposal (P <0.05) under all conditions. The incremental increase in glucose disposal after infusion tended to be higher following thyroid hormone treatment, but this was not statistically significant. However, the ratio of the incremental increase in glucose disposal to the increase in plasma insulin was significantly improved after thyroid hormone treatment in hypothyroid patients (P <0.05). It was also increased in healthy volunteers, but not significantly. We conclude that thyroid hormones improve the ability of insulin to stimulate glucose disposal related to insulinaemia. This phenomenon may be highly sensitive, because it was only apparent at low thyroid hormone levels.

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